AJP - Heart and Circulatory Physiology, Vol 244, Issue 1 73-H79, Copyright © 1983 by American Physiological Society
Influence of volume changes on osmolality-vasopressin relationships in conscious dogs
E. W. Quillen Jr and A. W. Cowley Jr
The relative importance of plasma osmolality (Posm) and left atrial
pressure (LAP) as controllers of plasma vasopressin concentration (PAVP)
was investigated in conscious dogs (n = 8). New techniques for the
continuous measurement of LAP and computerized data collection permitted
monitoring of LAP and mean arterial pressure (MAP) while Posm was
suppressed with intravenous distilled water and then elevated with
hypertonic NaCl. PAVP was determined by radioimmunoassay. This relationship
between Posm and PAVP was determined at low, normal, and high (-0.9 +/-
0.8, 1.8 +/- 0.8, and 7.7 +/- 1.1 cmH2O, respectively) levels of LAP
produced by either hemorrhage or autotransfusion of whole blood. MAP was
not altered by these maneuvers. The results of these short-term studies
have demonstrated a significant modulation of the osmoregulation of PAVP by
changes in blood volume as indexed by LAP. Because of this modulation, PAVP
is regulated so that contraction or expansion of the blood volume is more
expeditiously corrected than would occur if osmoreceptors alone regulated
plasma vasopressin.
